US3700576A - Ion-activity measuring electrode - Google Patents
Ion-activity measuring electrode Download PDFInfo
- Publication number
- US3700576A US3700576A US84300A US3700576DA US3700576A US 3700576 A US3700576 A US 3700576A US 84300 A US84300 A US 84300A US 3700576D A US3700576D A US 3700576DA US 3700576 A US3700576 A US 3700576A
- Authority
- US
- United States
- Prior art keywords
- cap
- electrode
- holder
- membrane
- ion
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/28—Electrolytic cell components
- G01N27/30—Electrodes, e.g. test electrodes; Half-cells
- G01N27/333—Ion-selective electrodes or membranes
- G01N27/3335—Ion-selective electrodes or membranes the membrane containing at least one organic component
Definitions
- This invention relates to measuring electrodes for the selective determination of the activity of certain ions in aqueous solutions which contain these ions in addition to other ions.
- the ion activity is, of course, a measure of the concentration of the ions in the given solution.
- permselective membranes there are, for example, those which are calcium-specific, other known membranes are sodium-specific still others are chloride-specific or fluoridespecific, and their selectivity is almost complete even if the aqueous solution containing the selected ions also contians very closely related ions, such as other alkaline earth metal, alkali metal or halide ions.
- This invention has the object to provide a measuring electrode for the selective measurement of ion activity in aqueous solutions, which has an especially simple design.
- the invention consists in a measuring electrode for the selective determination of cations or anions in aqueous solution, comprising a holder made of an electrically insulating material and including an electric conductor accessible at one end (terminal) of the holder where it forms the electrode proper, and a removable hollow cap fitting on the terminal of the holder and including in its wall a permselective membrane.
- cap Since the cap is removable it can be replaced when the membrane has become unserviceable. Similarly, two or more caps having membranes with different ion-specificities may be sold with one and the same holder. It is then possible to use the same electrode for different kinds of measurement by the simple exchange of the cap.
- the cap is filled with the appropriate standard electrolyte solution
- the membranecontaining tip of the electrode as well as a reference electrode are immersed in the test solution and the potential difference which then exists between the electrodes across the permselective membrane is measured by means of a voltmeter or analogous instrument inserted in the outer circuit between the electrodes.
- the potential difference thus determined is a function of the activity of the selected ions in the aqueous solution.
- the holder of the electrode is pencil-shaped and made of synthetic 3,700,576 Patented Oct. 24, 1972 resin, and the electric conductor within the holder is a wire anchored in the mass of the holder merging into, or being connectible with, the current lead of the outer circuit of the measuring apparatus.
- the terminal of the holder is designed to receive the cap by means of any suitable connection, e.g. a friction joint, or an outer thread provided on a boss constituting the terminal in continuation of the holder proper for cooperation with a corresponding tapped section of the cap, a bayonet catch, a snap catch or the like.
- the cap is also preferably made from synthetic resin.
- the permselective membrane is secured to the cap by a snap joint, as more fully described below, or by being fused into it.
- the entire electrode may be very small and handy, e.g. of about 10 to 15 cm. long and 10 to 15 mm. wide.
- FIG. 1 is a fragmentary axial section of an electrode according to the invention
- FIG. 2 is a fragmentary axial section, on a larger scale, of the cap.
- FIG. 3 is a diagrammatic representation of a measuring apparatus.
- the electrode here illustrated comprises a pencil-shaped holder 1 of synthetic resin, merging at one end (terminal) into a boss 2 provided with an outer thread 3.
- Anchored in the holder 1 is a metal wire 4 which projects from the terminal by an accessible length 4a, which is the electrode proper.
- the wire merges into the current lead 5 (FIG 3) of the outer circuit of the apparatus which is a conventional insulated wire.
- a cap 6 for holding a quantity of standard electrolyte solution and which tapers at its free end where it has an aperture 7.
- the latter is sealed by a plug 8 with axial bore 9 and carried at the free end of the bore a permselective membrane 10.
- the plug 8 has a collar 11 which, when the cap is assembed, snaps into an annular groove 12 provided in the tapering part of the cap 6. Instead, the plug 8 may be heat-sealed into the cap 6.
- the cap Before assembly, the cap is filled with the standard electrolyte solution so that the protruding end 4a of the wire 4 is immersed into the solution when the cap is screwed onto the holder.
- the measuring electrode as well as a reference electrode 15 are immersed in the test solution 13 contained in a beaker or vat 14.
- the outer circuit 5 between the measuring and reference electrodes includes a voltmeter 16, which indicates the potential difference between the two electrodes.
- a potassium-specific membrane was prepared by plasticizing a porous membrane of cellulose acetate, having a weak negative charge imparted to it by grafted-on carboxyl groups in accordance with copending application Ser. No. 40,350, filed May 25, 1970, which is assigned to the same assignee as the present application, with an 0.08% solution of valinomycin in dibutyl sebactate.
- the membrane was mounted in the electrode cap in the manner shown in FIG. 2.
- the cap was filled with a 10* molar aqueous solution of potassium chloride as standard.
- the electrode proper 4a (FIG. 1) was a silver-silver chloride standard electrode.
- the reference electrode was a conventional calomel electrode.
- the instrument 16 was a millivolt meter. The
- EXAMPLE 2 A calcium-specific membrane was prepared as a thin film by the evaporation of the solvent from a thin layer of a cyclohexane solution of polyvinyl chloride, tributylphosphate and fluoroyltrifluoroacetone in the weight ratio 1:3: 1. The membrane was fixed on the electrode cap which was then filled with a 10- molar aqueous solution of calcium chloride, whereafter the electrode cap was attached to the electrode holder. The measuring apparatus was the same as described in Example 1.
- EXAMPLE 3 A chloride-specific membrane was prepared by spreading a layer of dispersion of silver chloride in siloxane on a glass plate and curing it. The membrane was mounted on an electrode cap. Measurements performed as described in Example 1 showed that the electrode had a working range of 10- to 1 molar and that its selectivity for chloride ions with respect to bromide, iodide and nitrate ions was excellent. The life time of the membrane varied between 9 days and 2 months.
- EXAMPLE 4 An iodide-specific membrane was prepared by the same procedure as in Example 3, with silver iodide instead of silver chloride. The working range and selectivity were similar to those of the chloride-specific membrane of Example 3 but the life time of the membrane was only 12 days.
- a measuring electrode asembly for ion-activity measurements comprising:
- a cap forming a single reservoir in its interior space for holding the entire quantity of a standard electrolyte solution for the electrode assembly, said cap being removably interconnected to the holder behind the projecting tip, whereby the exposed tip of the conductor is immersed within the electrolyte solution and having an aperture in the bottom of the cap and an annular groove around the interior surface of the cap spaced from said aperature;
- a plug having an annular collar lockingly engaging the groove in the cap to hold the membrane in place over the aperture, said plug having a bore therethrough to connect the membrane with the solutio in the cap.
- the measuring electrode of claim 1 wherein the holder is pencil-shaped and made of synthetic resin, and the electric conductor is a wire anchored in the mass of the holder and connected with the current lead of a measuring apparatus.
Abstract
TACHED TO THE HOLDER. AN ION-SPECIFIC MEMBRANE IS LOCATED OVER AN APERTURE IN THE CAP AND THE CAP IS ADAPTED TO HOLD A STANDARD ELECTROLYTE SOLUTION.
Description
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
IL33983A IL33983A (en) | 1970-02-27 | 1970-02-27 | Ion-activity measuring electrode |
FR7106962A FR2135684A5 (en) | 1970-02-27 | 1971-03-01 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3700576A true US3700576A (en) | 1972-10-24 |
Family
ID=26216234
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US84300A Expired - Lifetime US3700576A (en) | 1970-02-27 | 1970-10-27 | Ion-activity measuring electrode |
Country Status (2)
Country | Link |
---|---|
US (1) | US3700576A (en) |
FR (1) | FR2135684A5 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4549951A (en) * | 1984-09-11 | 1985-10-29 | Sentech Medical Corporation | Ion selective electrode |
US5552032A (en) * | 1995-04-24 | 1996-09-03 | Beckman Instruments, Inc. | Solid state ion selective electrode and method of using the same |
US5571396A (en) * | 1993-07-12 | 1996-11-05 | Dade International Inc. | Fluid analysis system and sensing electrode, electrode assembly, and sensing module components |
-
1970
- 1970-10-27 US US84300A patent/US3700576A/en not_active Expired - Lifetime
-
1971
- 1971-03-01 FR FR7106962A patent/FR2135684A5/fr not_active Expired
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4549951A (en) * | 1984-09-11 | 1985-10-29 | Sentech Medical Corporation | Ion selective electrode |
WO1986001894A1 (en) * | 1984-09-11 | 1986-03-27 | Sentech Medical Corporation | Ion selective electrode |
US5571396A (en) * | 1993-07-12 | 1996-11-05 | Dade International Inc. | Fluid analysis system and sensing electrode, electrode assembly, and sensing module components |
US5552032A (en) * | 1995-04-24 | 1996-09-03 | Beckman Instruments, Inc. | Solid state ion selective electrode and method of using the same |
Also Published As
Publication number | Publication date |
---|---|
FR2135684A5 (en) | 1972-12-22 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: T-HYDRONAUTICS, INC., A CORP. OF TX, TEXAS Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:HYDRONAUTICS, INCORPORATED A CORP. OF MD;REEL/FRAME:004134/0357 Effective date: 19830509 Owner name: T-HYDRONAUTICS, INC., 6500 TRACOR LANE AUSTIN, TX Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:HYDRONAUTICS, INCORPORATED A CORP. OF MD;REEL/FRAME:004134/0357 Effective date: 19830509 |
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AS | Assignment |
Owner name: TRACOR HYDRONAUTICS Free format text: CHANGE OF NAME;ASSIGNOR:T-HYDRONAUTICS, INC.;REEL/FRAME:004186/0077 Effective date: 19830429 |
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AS | Assignment |
Owner name: TORONTO-DOMINION BANK, THE, AS AGENT Free format text: SECURITY INTEREST;ASSIGNOR:TRACOR, INC.,;REEL/FRAME:004810/0246 Effective date: 19871216 |
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Owner name: TORONTO-DOMINION BANK, THE Free format text: SECURITY INTEREST;ASSIGNORS:TRACOR, INC.;LITTLEFUSE, INC.;TRACOR AEROSPACE, INC.;AND OTHERS;REEL/FRAME:005234/0127 Effective date: 19880801 Owner name: BANK OF AMERICA NATIONAL TRUST AND SAVINGS ASSOCIA Free format text: SECURITY INTEREST;ASSIGNORS:TORONTO-DOMINION BANK;TRACOR, INC.;REEL/FRAME:005224/0276 Effective date: 19880801 Owner name: BANK OF AMERICA NATIONAL TRUST AND SAVINGS ASSOCIA Free format text: SECURITY INTEREST;ASSIGNOR:TRACOR, INC.;REEL/FRAME:005217/0247 Effective date: 19880801 Owner name: BANK OF AMERICA NATIONAL TRUST AND SAVINGS ASSOCIA Free format text: SECURITY INTEREST;ASSIGNOR:TRACOR INC.;REEL/FRAME:005217/0224 Effective date: 19880801 Owner name: BANK OF AMERICA AS AGENT Free format text: SECURITY INTEREST;ASSIGNOR:TORONTO-DOMINION BANK, THE;REEL/FRAME:005197/0122 Effective date: 19880801 |
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AS | Assignment |
Owner name: TRACOR, INC. Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:BANK OF AMERICA NATIONAL TRUST AND SAVINGS ASSOCIATION AS COLLATERAL AGENT;REEL/FRAME:005957/0562 Effective date: 19911220 Owner name: TRACOR, INC. Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:BANK OF AMERICA NATIONAL TRUST AND SAVINGS ASSOCIATION AS COLLATERAL AGENT;REEL/FRAME:005957/0542 Effective date: 19911227 |